Grayback-Sucker
Water Quality Management Plan
Siskiyou National Forest

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PARAMETER 2, HABITAT MODIFICATION

Determining overall channel conditions and the biological potential of fish-bearing stream segments from stream survey data has been ongoing for several decades in the Pacific Northwest. Analyzing stream survey data for the Grayback-Sucker Creek Water Quality Management Plan concentrated on five attributes at the stream reach scale: riffle width, pool frequency, pool area, large wood and riparian forest seral stage.

Except for riparian forest seral stage, the attributes have been agreed to by Federal and State teams in Oregon, as core attributes in stream survey protocols and useful to assess stream conditions. These parameters are included on the "Interagency Aquatic Database and GIS" which is a compilation of stream surveys from various agencies in Oregon. These stream survey attributes are inventoried by the Forest Service, Bureau of Land Management and the Oregon Department of Fish and Wildlife (ODFW) with protocols that are comparable. It was decided to include riparian forest seral stage in this discussion because of important relationships between aquatic and riparian functions. The data used for this analysis is from ODFW and Forest Service stream surveys.
 

To rate the five attributes as Poor, Fair and Good; the ODFW benchmarks developed from hundreds of miles of stream surveys in Western Oregon were employed. This table is included in the Appendix as "ODFW:Aquatic Inventory Project: Habitat Benchmarks", Table 1 and Appendix C. Additionally, monitoring and watershed analysis information for these attributes on the Siskiyou National Forest was used to adjust these benchmarks to unique stream and riparian conditions found in Klamath Mountain geology. The Poor, Fair and Good ratings should be viewed as relative, with the diversity of conditions in Sucker Creek and Grayback Creek, and helpful for a reference to compare across watersheds with similar ecological conditions. Figure 4 depicts in a profile graph the relative stream and riparian conditions of the stream reaches analyzed. Upper Sucker Creek is a 6th field watershed and Grayback Creek is a 6th field sub-watershed within the Sucker Creek 5th field watershed. For the following discussion, Sucker Creek refers to the upper Sucker Creek sub-watershed with Grayback Creek as a major tributary, unless Grayback Creek is specifically named. Table 8 shows the numeric values for the stream segments discussed in the Sucker Creek watershed.

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Individual Attribute Discussion:

Riffle Width: This attribute is the average wetted riffle width of the stream reach surveyed. Less observer bias is associated with wetted width than bankfull width, per stream survey quality control monitoring. Riffle width was used here to calculate pool frequency.

Pool Frequency: Pool frequency was calculated by dividing the number of pools in the reach by the number of riffle widths in the reach length. Therefore, a pool frequency of 1/10 or 0.1 would translate to one pool per ten (10) wetted widths. A pool frequency of 0.1 or higher would be expected in a functioning low gradient reach (<3% gradient) with pool/riffle morphology. Some allowance was made in transport reaches where step/pool morphology forms more frequent and shorter pools.

Pool Area: Pool area is calculated by dividing the surface area of pool habitat by the total surface area of wetted habitat surveyed. Similarly to the discussion for pool frequency, some allowance must be made for different morphologies of pool/riffle and step/pool stream reaches.

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Large Wood Material: Large wood is included in this rating only if the dimensions are large enough to function as a key piece to collect smaller pieces of wood in complexes. Grayback Creek and upper Sucker Creek sub-watersheds are approximately 20,000 and 26,000 acres respectively in size. Small pieces of wood will not hold in these channels without key pieces of large wood present. Wood is primarily present in complexes in these two streams. Diameters of these key pieces are equal to or greater than 24 inches and the length is 50 feet or twice the bankfull width.

Riparian Forest Seral Stages: ODFW, BLM and Forest Service stream surveys measure the relative size of trees in the riparian zones along fish-bearing streams. The outer riparian zone, twenty-five (25') feet from the bankfull edge to one hundred (100') feet from the bankfull edge was used here for rating the health of the riparian zones. The outer riparian zone is generally beyond the alder and hardwood vegetation buffer many stream channels have in Grayback/ Sucker Creek. One would expect to find a dominant component of mature conifers and some hardwoods in this portion of the riparian zone. Examination of aerial photos from 1939-40 indicate that streamside vegetation generally was in mature stage, even if surrounding upslope vegetation appeared to be in an earlier successional stage from fire. For comparative purposes, the expected condition of seventy-five percent (75%) large trees greater than twenty inches (20") diameter are designated as LT. Trees less than twenty inches in diameter are designated as small trees or ST. Sucker Creek watershed generally is a high site for conifer tree growth, most areas are capable of rapid conifer growth and this watershed is capable of producing very large trees in floodplains and terraces.

In the upper stream reaches of both Sucker Creek and Grayback Creek the riparian and aquatic habitat are generally in FAIR to GOOD condition. The exception is Reach 2 in Grayback Creek, where the riparian zone is in a very young seral stage and rated POOR. The low gradient response reaches, potentially high for biological productivity, are among the most altered by mining, harvest and flood repair work from past storm events. These low gradient reaches have very high biological potential, sensitive to alteration and tend to be most accessible to management activities. The aquatic habitat is considerably less than optimum for production of salmonids, particularly coho salmon, which require the full suite of freshwater habitat components. Coho salmon and coho salmon critical habitat are listed under the Endangered Species Act. Coho require quality pool habitat during summer months and off channel or alcove habitat on the floodplain during the winter months. Coho salmon tend to inhabit low gradient stream reaches.

Inherently, Sucker Creek is a high value salmonid fish watershed. It is one of the few watersheds in the Siskiyou Mountains with substantive snowpack most years and good cold-water flow during the summer months. Despite the human alterations caused by mining, timber harvest and downstream agriculture uses; Sucker Creek has good numbers of coho salmon, Chinook salmon and winter steelhead spawning during many years. Sucker Creek is a very high priority for protection and restoration, and one of the most important anadromous fish watersheds in the Rogue River basin.

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Benchmarks for Evaluating Stream Survey Data
For Water Quality Management Plan
Sucker Creek - Siskiyou National Forest 

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Table 8 – Habitat Comparisons for Selected Reaches in Sucker Creek and Grayback Creek

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	Figure 4 –  Profiles of Sucker Creek and Grayback Creek Reaches with Habitat Rating ^^ Back to Above Text